Means for applying a trimming condenser to a main condenser



Dec. 15, 1936 D |BBY 2,064,620'

MEANS FOR APPLYING A TRIMMIIQG CONDENSER TO A MAIN CONDENSER Filed July30', 1932 FIG. 1' 9 7 ll 8 I (O 4 6 h II P- l" l ll 0 In I] CE- WW: 30 lI I a I 27 I3 I I4 Z5 I 2 v 1 HI 3 26 a 2 I6 17 I f INVENTOR ALBION D.T. LIBBY Patented Dec. 15, 1936 PATENT omcs MEANS FOR APPLYING A G- con-TBIHMIN DENSER TO 'A MAIN CONDENSER Albion D. '1. Libby, East Orange, N.1., assignor to Condenser Development Corporation, Newark,

Application July 30, 1932, Serial No. 626,452

3Claims.

This invention relates to improvements in the design of variableelectrical condensers such as used in radio receiving sets.

In the design of gang condensers, it is the usual practice to provideeach condenser unit with what is known in the trade as a trimmer. Thistrimmer condenser ordinarily consists of a single plate mounted so as tofunction in parallel with its associated main condenser unit, wherebythe initial capacity of the main condenser may be slightly varied byadjustment of the trimmer plate.

It is also quite the usualpractice to provide the main condenserunitswith some compensating means whereby the capacity curve of the condensermay be automatically varied over its-range in order that the varioustunable circuits may be brought as near alike as possible to the maximumtuning point at various settings of the tuning dial. Various otherfeatures are sometimes specifled by the receiving set manufacturers sothat the condenser manufacturer must be imposition to furnishcondensersthat will meet all the various requirements which may or maynot include the trimmer condenser.

If the gang condenser can be built and placed in stock without thetrimmer condenser, but arranged so that the same may be readily addedwithout changing the adjustment of the various Y units of the gang, muchtime and expense can be saved when an order is received requiring atrimmer plate. w

My invention is directed to means for quickly attaching the trimmercondenser without disturbing the normal calibration ofthe main condenserwith which it is associated, so that if the condenser manufacturer, onreceipt of an order, has condensers in stock without the trimmer, and atrimmer is required, the same may be quickly added; orif the condensersin stock have trimmers thereon and the order calls for tuning condenserswithout trimmers, these trimmer plates may be quickly removed withoutdisturbing the adjustments that have already been made on the maincondenser.

Another object of my invention is to provide means for mounting atrimmer condenser which is applicable to a gang condenser of the compacttype; that is to say, one in which the condenser units are small orcompressed in dimensions, as well as one where the mounting space isnotlimited. Y

My improvement is shown in the annexed draw- 1 ing, in connection witha-two-gang condenser, but

it is to be understood that'any number of condenser units may beincluded in the gang. In the drawing:

Figure 1 illustrates a side elevation of a twogang condenser in whichthe groups of rotor plates are in partial engagement with theirrespective stator plates, one of the units of the gang being equippedwith a trimmer plate, while on the other unit the trimmer plate has beenremoved to show certain details.

Figure 2 is a fragmentary sectional view on the line 22 of Figure l.

Figure 3 is a view on an enlarged scale of the preferred form of meansfor'mounting the main and trimmer condensers.

In the drawing, 1 is a frame having end-support plates 2 and 3 carryingan operating shaft 4 suported preferably on anti-friction bearingmembers carried in the races 5 and 6, all as shown and described inCramer Patent 1,800,719, issued April 14, 1931. The shaft 4 carriessleeves I and 8 to which the rotor groups of. plates 8 and II areattached in any satisfactory manner. As illustrated, the outer ends ofthe rotor plates 0 are fastened together by tieplate ll, while the outerends of the groups of rotor plates III are fastened together bytie-plate l2.

The side members of the frame I have openings l3 and It therein withupturned lugs l5 and It projecting a short distance into these openings.Fastened to the lugs I! and it in any satisfactory manner, as by rivetsII, are insulators II. To the other ends of the insulators I. areattached the stator group of plates IS. The plates is are provided withnotches or recesses 20 over which a tie-bar II is positioned, and towhich tie-bar the plates I! are fastened in any satisfactory manner.

' screw 23', while having an external thread 2|,is

also provided with an internal thread 25. The internal threadllis'adapted to receive an auxiliaryfastening means or screw 26 whichlatterscrew is-adapted to mount the trimmer condenser plate 21 on theinsulator It. It will be seen from Figures 2 and 3 that the trimmerplate will be clamped by the auxiliary "screws 26 against the heads II,to the main fastening means or screws The trimmer condenser plate 21overlaps the frame I as'shown in Figures 1' and 2, and is kept fromelectrical contact therewith by an insulator 29, and adjusted withrespect thereto by means of an adjusting screw 30 insulated from thetrimmer plate 21 by an insulator 3|. The lower end of the trimmer plate2'! ends in a terminal 32 to which electrical connections may be made.Electrical connection to each stator may be made by means of a smallclip permanently fastened under the head 28 of the screw 24; or as issome times done, it may be made by the clip being mounted under theheads of the corresponding standard screws on the opposite side of thecondenser in the usual manner.

From what has been said, it will be readily understood that the mainfasteners or screws 23 which are used for mounting the main condenser asexplained, are much heavier than the screws 26, and when the mainfastening screws 13 are set up, the main condenser is rigidly held inplace. Since the auxiliary screws 26 are independent of the mountingscrews 23, it will be seen that the trimmer plate may be put on or takenoff without in any way disturbing the main mounting screws or thesetting of the main condenser, and no additional mounting means arerequired on the insulators l8.

Having thus described my invention, what I claim is:

1. For an electrical condenser having a frame and relatively movablesets of elements carried thereon and also having means for attaching oneset of said elements to at least two insulators carried by the frame,said attachment means including members going through the insulators; atrimmer condenser plate adapted to be quickly mounted on the insulatorby means directly engaging said attachment members but withoutdisturbing the same, and means for adjusting the capacity position ofsaid trimmer plate with respect to the frame.

2. For an electrical condenser having a frame and relatively movablesets of elements carried thereon and also having means for attaching oneset of said elements to at least two insulators carried by the frame,said attachment means including members going through the insulators; atrimmer condenser plate adapted to be quickly mounted on the insulatorby means of independently operated screws going directly into certain ofsaid attachment members, and means for adjusting the capacity positionof said trimmer plate with respect to the frame.

3. Means for mounting a trimmer condenser plate in operative relation toa main condenser and its supporting frame, said means including screwsfor assisting in fastening the main condenser'to the frame, at least apart of said screws having an internal thread as well as an externalthread, and auxiliary screws threaded into the internal threads of saidfirst-mentioned screws for holding the trimmer plate against the headsof said first-mentioned screws.

ALBION D. T. LIBBY.

